St. Helena Wastewater Facilities Evaluation Update

Achieving Regional Water Quality Control Board Compliance

The City of St. Helena’s Wastewater Treatment and Reclamation Plant (WWTRP) is operated under a discharge permit issued by the Regional Water Quality Control Board (RWQCB). The permit included requirements to improve and/or convert portions of the facility to meet capacity requirements for an outdated city growth projection. However, recent and projected growth, coupled with changes in water use patterns,  changed the magnitude and nature of necessary improvements. An updated Report of Waste Discharge and permit application was needed for the RWQCB. The city also needed to update WWTRP facilities improvement planning to meet the projections for flow and load – in advance of submitting a permit application to the RWQCB.

Bennett Engineering Services reviewed available planning and evaluation documents and prepared an updated memorandum for treatment capacity and effluent quality improvements necessary to meet the current projections for flows and loads. Specific discussion items included design flows and loads for projections within the available planning horizon, modifications or improvements to address capacity and effluent quality, algae reduction options, and disinfection system improvement options and recommendations.